Trump, who re­quested Ses­sions’ res­ig­na­tion, named Matthew Whi­taker to serve as in­terim at­tor­ney gen­eral. Whi­taker was Ses­sions’ chief of staff and had been con­sid­ered for a va­ri­ety of jobs in the Trump ad­min­is­tra­tion, in­clud­ing the No. 2 post at Jus­tice or as White House coun­sel.

In his new role, Whi­taker also will over­see spe­cial coun­sel Robert Mueller’s Rus­sia in­ves­ti­ga­tion, prompt­ing

fears among Demo­cratic law­mak­ers that Trump was seek­ing to de­rail the probe as it nears an end.

“Since the day I was hon­ored to be sworn in as at­tor­ney gen­eral of the United States, I came to work at the Depart­ment of Jus­tice ev­ery day de­ter­mined to do my duty and serve my coun­try,” Ses­sions said in a sev­en­para­graph let­ter. “I have done so to the best of my abil­ity to sup­port the fun­da­men­tal le­gal pro­cesses that are the foun­da­tion of jus­tice.”

Deputy At­tor­ney Gen­eral Rod Rosen­stein, who had been over­see­ing Mueller’s in­ves­ti­ga­tion un­til Whi­taker’s ap­point­ment, was at the White House on Wed­nes­day af­ter­noon for a meet­ing, though he re­mained in his job. He was among those in an en­tourage of Jus­tice lead­ers who ac­com­pa­nied Ses­sions as he ex­ited the depart­ment for the last time Wed­nes­day night.

In a state­ment later Wed­nes­day, Whi­taker called his ap­point­ment a “true honor.”

“I am com­mit­ted to lead­ing a fair depart­ment with the high­est eth­i­cal stan­dards, that upholds the rule of law, and seeks jus­tice for all Amer­i­cans,” Whi­taker said.

He de­scribed Ses­sions as “a ded­i­cated pub­lic ser­vant.”

“It has been a priv­i­lege to work un­der his lead­er­ship,” Whi­taker said. “He is a man of in­tegrity who has served this na­tion well.”

The de­par­ture of Ses­sions, one of Trump’s most vo­cal and ear­li­est sup­port­ers dur­ing the 2016 cam­paign, was ex­pected for weeks.

Laser-fo­cused on Ses­sions’ de­ci­sion to re­cuse him­self from the Rus­sia in­ves­ti­ga­tion, Trump sav­aged him in in­ter­views, tweets and news con­fer­ences as “be­lea­guered,” of­ten ex­press­ing “dis­ap­point­ment” in his at­tor­ney gen­eral.

“I don’t have an at­tor­ney gen­eral. It’s very sad,” Trump said in a Septem­ber in­ter­view with Hill.TV. “I’m not happy at the bor­der, I’m not happy with nu­mer­ous things, not just this.”

Ses­sions’ re­cusal in March 2017 for fail­ing to dis­close elec­tion-year meet­ings with Rus­sian Am­bas­sador Sergey Kislyak – and Trump’s dis­missal of FBI Di­rec­tor James Comey in May 2017 – prompted the ap­point­ment of Mueller, a for­mer FBI di­rec­tor, as the Jus­tice Depart­ment’s spe­cial coun­sel to di­rect the wide-rang­ing Rus­sia in­quiry.

Mueller’s ap­point­ment and the in­quiry’s ex­pan­sion to in­clude a deep ex­am­i­na­tion of the Trump fam­ily’s finances and pos­si­ble ob­struc­tion of jus­tice stoked the pres­i­dent’s at­tacks on the at­tor­ney gen­eral.

“I think you have to ask the ques­tion of who benefits from Ses­sions’ re­moval,” said Jimmy Gu­rule, who was an as­sis­tant at­tor­ney gen­eral un­der Pres­i­dent Ge­orge H.W. Bush. “And the an­swer is Pres­i­dent Trump.”

“He’s done all this un­der enor­mous pres­sure, and we know what that is,” Mukasey told USA TO­DAY, re­fer­ring to un­re­lent­ing crit­i­cism from the pres­i­dent. “I can’t imag­ine how he’s been able to do this.”

Rather than walk away in the face of Trump’s at­tacks, Mukasey said, Ses­sions re­mained at the helm of the sprawl­ing agency “for the wel­fare of the depart­ment.”

“For him to have done that is in­cred­i­ble,” Mukasey said.

In July 2017, Trump told The New York Times he would never have ap­pointed the for­mer Alabama sen­a­tor had he known Ses­sions would dis­qual­ify him­self from over­see­ing the Rus­sia in­ves­ti­ga­tion. He re­peated the line in a Rose Gar­den news con­fer­ence the fol­low­ing week. “If he was go­ing to re­cuse him­self, he should have told me prior to tak­ing office, and I would have, quite sim­ply, picked some­body else,” Trump said.

“I’m not happy at the bor­der, I’m not happy with nu­mer­ous things, not just this.”